Phonation Analysis Combined with 3D Reconstruction of the Thyroarytenoid Muscle in Aged Ovine Ex Vivo Larynx Models.

OBJECTIVE

The aim of the study was to establish a basic data set of combined functional and anatomical measures of aged sheep larynges using ex vivo models. Combining these two approaches in one and the same larynx is an unmet goal so far yet is important as newer treatment strategies aim to preserve the organ structure and new assessment tools are required. Ovine larynges were used as their dimensions, and muscle fiber type distribution highly resemble the human larynx.

STUDY DESIGN

Ex vivo animal study.

METHODS

Larynges of six sheep (~9 years of age) were subjected to ex vivo functional phonatory experiments. Phonatory characteristics were analyzed as a function of longitudinal vocal fold (VF) prestress. Anatomical measurements of the same larynges comprised micro-computed tomography scans followed by three-dimensional (3D) reconstructions. Using specially adapted radiological scan protocols with subsequent 3D reconstruction, muscle volumes, surface areas, and anatomical measurements were computed.

RESULTS

Increasing longitudinal prestress yielded higher subglottal pressure (P) for the same airflow. Quantitative differences to previous studies-such as the increased P and increased phonation threshold pressure-were detected. We achieved excellent visualization of the laryngeal muscles and framework, resulting in accurate 3D reconstructions for quantitative analysis. We found no significant intraindividual volume differences of the thyroarytenoid muscles.

CONCLUSION

The established protocol allows precise functional and anatomical measures. The data created provide a reference data set for upcoming therapeutic strategies (eg, growth factor therapy, functional electrical stimulation) that target essential structures of the VFs such as the laryngeal muscles and/or the VF mucosa.